Symmetrical bis-salophen probe serves as a selectively and sensitively fluorescent switch of gallium ions in living...

Area of Science:

• Analytical Chemistry
• Bioinorganic Chemistry
• Materials Science

Background:

• Gallium compounds exhibit significant bio-activities and are explored for treating refractory malignancies.
• Monitoring gallium compounds in vivo is crucial for therapeutic applications.
• Existing methods for gallium detection may lack the required selectivity or sensitivity for biological systems.

Purpose of the Study:

• To design and synthesize a novel fluorescent probe for selective and sensitive detection of gallium ions (Ga3+).
• To investigate the sensing mechanism and biological applicability of the developed probe.
• To enable real-time tracking of gallium compounds in biological models.

Main Methods:

• Synthesis of the N,N",N"',N""-Tetrakis(2-hydroxybenzylidene)biphenyl-3,3',4,4'-tetramine (bis-salophen) fluorescent probe.
• Spectroscopic analysis (fluorescence, UV-Vis) to characterize probe-Ga3+ interaction, including stoichiometry, association constant, and limit of detection.
• Density Functional Theory (DFT) calculations to elucidate the sensing mechanism.
• In vitro evaluation in normal and cancer cell lines for biological applicability.
• In vivo imaging in zebrafish models.

Main Results:

• The bis-salophen probe selectively and sensitively detects Ga3+ ions via a fluorescence "turn on" mechanism.
• Spectroscopic studies revealed a 1:2 probe-Ga3+ stoichiometry with an association constant of 8.85 × 10^6 M-1 and a limit of detection of 13.0 nM.
• DFT analysis indicated that Ga3+ binding suppresses photoinduced electron transfer (PET) and interrupts π-conjugation.
• The probe demonstrated high selectivity and sensitivity for cancer cells in vitro.
• Successful imaging of Ga3+ ions in living zebrafish was achieved.

Conclusions:

• A novel bis-salophen fluorescent probe for Ga3+ detection has been successfully developed.
• The probe exhibits excellent selectivity, sensitivity, and biological applicability for detecting Ga3+ in living cells and zebrafish.
• This work provides a valuable tool for monitoring gallium in biological and medical applications.